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Dimensions

In the NetCDF data model, dimensions have names and a length (but possibly an unlimited length) and are defined for a NetCDF dataset (or group). For a given Variable or CFVariable,the names of the corresponding dimensions are obtained with using dimnames.

Base.keys — Method
keys(d::Dimensions)

Return a list of all dimension names in NCDataset ds.

Examples

ds = NCDataset("results.nc", "r");
dimnames = keys(ds.dim)
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Base.haskey — Method
haskey(ds::NCDataset,name)
haskey(d::Dimensions,name)
haskey(ds::Attributes,name)

Return true if the NCDataset ds (or dimension/attribute list) has a variable (dimension/attribute) with the name name. For example:

ds = NCDataset("/tmp/test.nc","r")
if haskey(ds,"temperature")
    println("The file has a variable 'temperature'")
end

if haskey(ds.dim,"lon")
    println("The file has a dimension 'lon'")
end

This example checks if the file /tmp/test.nc has a variable with the name temperature and a dimension with the name lon.

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CommonDataModel.defDim — Function
defDim(ds::NCDataset,name,len)

Define a dimension in the data set ds with the given name and length len. If len is the special value Inf, then the dimension is considered as unlimited, i.e. it will grow as data is added to the NetCDF file.

For example:

using NCDatasets
ds = NCDataset("/tmp/test.nc","c")
defDim(ds,"lon",100)
# [...]
close(ds)

This defines the dimension lon with the size 100.

To create a variable with an unlimited dimensions use for example:

using NCDatasets
ds = NCDataset("/tmp/test2.nc","c")
defDim(ds,"lon",10)
defDim(ds,"lat",10)
defDim(ds,"time",Inf)
defVar(ds,"unlimited_variable",Float64,("lon","lat","time"))
@show ds.dim["time"]
# returns 0 as no data is added
ds["unlimited_variable"][:,:,1:4] = randn(10,10,4)
@show ds.dim["time"]
# returns now 4 as 4 time slice have been added
close(ds)
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CommonDatamodel.defDim(ds::AbstractDataset,name::SymbolOrString,len)

Create dimension with the name name in the data set ds with the length len. len can be Inf for unlimited dimensions.

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Base.setindex! — Method
setindex!(d::Dimensions,len,name::AbstractString)

Defines the dimension called name to the length len, for example:

ds = NCDataset("file.nc","c")
ds.dim["longitude"] = 100

If len is the special value Inf, then the dimension is considered as unlimited, i.e. it will grow as data is added to the NetCDF file.

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NCDatasets.renameDim — Method
renameDim(ds::NCDataset,oldname::SymbolOrString,newname::SymbolOrString)

Renames the dimenion oldname in the dataset ds with the name newname.

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One can iterate over a list of dimensions as follows:

for (dimname,dim) in ds.dim
    # all dimensions
    @show (dimname,dim)
end